At Tech Etch, we use a photo-etching process to manufacture light-gauge metal parts. This process allows us to create metal components with exacting tolerances that cannot be created through another process.

All configurations, tolerances, and dimensions are functions of the metal thickness. The guide on this page goes over the practical limitations of the photo-etching process. Here, you’ll learn the limitations and requirements for slots, spaces, holes, and construction dimensions of your metal parts.

In certain cases, these limitations can be exceeded but with a reduction in yield percentage. The Figures to the left offers a visual representation of these features. Speak with our team for design assistance when you need to go beyond these limitations.


Holes and slots

Generally, the width of a slot or the diameter of a hole can’t be smaller than the thickness of the metal part. This measure can change as the metal becomes thicker. A more exact relationship is illustrated in Table 1.

Inside corner radius

The smallest inside corner radius is proportional to the thickness of the material. Talk to our factory if smaller or sharper radii are required.

Table 1: Holes or Slot

Metal Thickness (T) Diameter or Width
.001″-.005″ 1.1 Times Metal Thickness
(Min. .003″)
.005″ or Over Min. of 1.1 Times Metal Thickness

Fingers and webs

Typically, the finger or web width needs to be at least the same size as the material thickness. As the material thickness changes, this measure also changes. A more exact relationship is illustrated in Table 2.

Outside corner radius

The outside corner radius must be at least 75 percent of the material’s thickness.

Table 2: Web or Finger

Spaces Between Holes (W) At Least Metal Thickness


Center to center

Generally, the stability of the photo tooling material is the basis for the tolerances of the material. Consult our team for more information on alternate tooling materials.  Table 3 illustrates the practical tolerances attainable from industry standard Mylar tooling.

Photo-etched dimensions

It’s practical to have a tolerance of ± 15 percent of the material thickness. A more exact relationship is illustrated in Table 4.

Table 3: Center to Center Tolerances

C/C Dimensions (inches) Tolerance Attainable
 1.0″ or Less  ±.0005″
 1.0″ – 3.0″ ±.0010″
 3.0″ – 6.0″  ±.0020″
 6.0″ – 10.0″  ±.0030″

Table 4: Etched Dimension Tolerances

.001″ .002″ .005″ .010″ .015″ .020″ .040″
Empirical ±.0010″ ±.0010″ ±.0015″ ±.0020″ ±.0030″ ±.0050″

Thickness (T) (inches)